JP4956964B2 - Robot hand gripping control device - Google Patents

Description

  The present invention relates to a robot hand grip control device that performs grip control of a robot hand having a plurality of finger members each including a plurality of link members connected via joints.

  As a prior art for gripping an object using a robot hand, there is a robot control method disclosed in Japanese Patent Application Laid-Open No. 2003-245883. In this robot control method, when gripping an object using a robot hand, each joint is strongly squeezed at a predetermined speed when not in contact, and when the finger link contacts the object, the base side of the contacted finger link The force is controlled so that the contact force acting on the link becomes the target contact force.

As another prior art, there is a robot hand with hand vision disclosed in Japanese Patent Laid-Open No. 2003-94367. The robot hand with hand vision generates gripping position data for gripping the workpiece from the shape and position of the captured workpiece, changes the gripping position of the robot hand based on the gripping position data, and makes the robot hand autonomous Thus, the workpiece can be gripped at the optimum gripping position.
JP 2003-245883 A JP 2003-94367 A

  However, the robot control method disclosed in Patent Document 1 grips an object without predicting the gripping posture. For this reason, depending on the position of the finger link, the number of contact points between the object and the finger link may be reduced, and gripping may occur in an unstable state. In addition, since the contact force is used, there is a possibility that the finger link that has previously contacted the object may move, defeat, or damage the light object or the unstable object.

  Further, the robot hand with hand vision disclosed in Patent Document 2 determines a gripping position of the robot hand based on the captured shape and position of the workpiece and grips the workpiece. However, a specific method for gripping the workpiece by the robot hand has not been disclosed, and it cannot be said that the workpiece can be reliably gripped.

  Furthermore, if the work is too large or conversely too small, there are often fewer finger links and contact points, which increases the possibility of gripping in an unstable state. It was.

  Accordingly, an object of the present invention is to provide a grip control device for a robot hand that can reliably grip an object with a low risk of falling or damaging the object by a finger member.

A gripping control device for a robot hand according to the present invention that solves the above-described problems is a finger in a hand member having a finger member having a plurality of link members connected via nodes and a palm member to which the finger member is attached. In a grip control device of a robot hand that grips an object to be gripped by controlling the angle of each joint of the member, a thumb member is disposed at a position facing the finger member with the palm member sandwiched on one side of the palm member, A pair of hand members are arranged as hand members, and an object shape recognition unit that recognizes the shape of the gripping target object, an object size recognition unit that recognizes the size of the gripping target object, and the shape of the recognized gripping target object Based on the above, a joint angle when a plurality of link members included in the finger member are in contact with the gripping target object is obtained, and the gripping posture of the finger member is calculated according to the obtained joint angle A force calculating means and a joint angle control means for controlling the respective joints so that the finger member is in a posture obtained by the gripping posture calculating means. The gripping posture calculating means includes a plurality of predefined model shapes and A grip calculation method corresponding to the model shape, a grip format corresponding to the model size of the object to be gripped, and a contact condition between the model shape determined from the constraint condition of the robot hand with respect to the model shape and the palm member and the finger member. One of a plurality of model shapes is assigned to the shape of the grasped and recognized gripping target object, and the robot is selected based on the model shape assigned to the gripping target member from the stored gripping calculation methods. Select the grip calculation method for gripping the object with the hand, and select the gripping format from the stored gripping formats according to the size of the recognized gripping target object. Among the stored contact conditions, when gripping the gripping target object in the selected gripping format, the gripping posture satisfying the contact condition between the model shape assigned to the gripping target object and the palm member and the finger member is selected. When calculating by the grip calculation method, the grip posture satisfying the contact condition between the grip target object and the thumb member and the finger member is calculated, and the grip posture satisfying the contact condition between the model shape and the finger member and the thumb member is calculated. If it is determined that the gripping posture satisfying the contact condition between the model shape and the palm member and the finger member is calculated, the range covering the model shape assigned to the gripping target member by the finger member and the thumb member is a predetermined range. When it is smaller, the gripping posture that satisfies the contact condition between the pair of hand members and the model shape is calculated .

  In the grip control device for a robot hand according to the present invention, any one of a plurality of model shapes is assigned to the shape of the object to be gripped, and a grip posture satisfying a contact condition between the assigned model shape and the palm member and the finger member Is calculated. Therefore, for example, according to the size of the gripping target object, it can be determined whether the gripping target object is gripped by contacting the palm member and the finger member, or whether the gripping target object is gripped only by the finger member. . Therefore, there is a low risk of the object being brought down or damaged by the finger member, and the object to be grasped can be reliably grasped.

  Examples of the “model shape” in the present invention include a rectangular shape, a cylinder, a sphere shape, a ring shape used as a cup handle, and the like. Furthermore, in addition to these shapes, the shapes of objects that can be gripped by the robot can be roughly classified.

  When the model shape to which the gripping target object is assigned is large, there is a gripping posture that satisfies the contact condition between the model shape and the palm member and the finger member, but when the model shape is small, the gripping posture that satisfies the contact condition is satisfied. Will not exist. In this case, according to the present invention, it is possible to calculate a gripping posture that satisfies the contact condition between the model shape and the finger member, and to grip the gripping target object only with the finger member. Therefore, the object to be grasped can be grasped more reliably.

  When the model shape to which the gripping target object is allocated is somewhat large, the gripping target object can be gripped by the finger member and the thumb member, but when the model shape is small, the finger member and the thumb member grip the gripping target object. I can't. In this case, the object to be grasped can be more reliably grasped by obtaining the contact conditions between the model shape and the palm member and the finger member.

  Further, a pair of hand members are disposed as the hand members, and the gripping posture calculation means is configured so that the pair of hand members and the model shape when the range in which the grip target member is wrapped by the finger member and the thumb member is smaller than a predetermined range. It is also possible to calculate the gripping posture that satisfies the contact condition.

  When the model shape to which the gripping target object is allocated is very large and the range in which the gripping target member is wrapped by the finger member and the thumb member is smaller than a predetermined range, for example, less than half of the gripping target object, the gripping target object is It cannot be gripped by the thumb member. In this case, the gripping target object can be gripped by the pair of hand members by calculating the gripping posture that satisfies the contact condition between the pair of hand members and the model shape.

  Further, at least a part of the joints are interlocking joints that link the link members to be connected, and the gripping posture calculation unit calculates the gripping posture when it determines that there is no gripping posture that satisfies the contact condition with the palm member and the finger member. It can also be set as the aspect which changes the position with respect to the holding | grip object of the hand member used for.

  Thus, by using an interlocking joint as the joint of the link member, it is possible to reduce the amount of calculation when calculating the gripping posture of the finger member. Here, when at least a part of the joints are interlocking joints, the gripping posture calculation means for the gripping target object and the finger member has a severe contact condition between the palm member and the finger member, and grips the gripping target object. It is difficult to secure the number of contact points when obtaining the gripping posture.

  In contrast, when the grip control device for the robot hand according to the present invention determines that there is no gripping posture that satisfies the contact condition with the palm member and the finger member, the position of the hand member used for gripping posture calculation with respect to the gripping target object To change. For this reason, when it is determined that there is no gripping posture that satisfies the contact condition with the palm member and the finger member, the gripping target member can be gripped by the finger member by changing the position of the hand member with respect to the gripping target object. It is possible to easily find the gripping posture.

  The contact condition is a condition obtained by geometrically determining the position of the finger member relative to the object when the object to be grasped and the finger member have a predetermined number of contact points or more from the model shape and the constraint condition of the robot hand. It can also be set as the aspect which is.

  The predetermined number referred to in the present invention is preferably the maximum number of contact points geometrically determined from the model shape and the constraint conditions of the robot. Thus, the most stable gripping state can be obtained by gripping with the maximum number of contact points.

  Furthermore, an object position recognizing unit for recognizing the position of the gripping target object and a hand member position control unit for controlling the position of the hand member are provided, and the relative position between the recognized position of the gripping target object and the position of the hand member is provided. It is also possible to adopt a mode in which the position of the hand member is controlled based on various positional relationships.

  Hand member position control means for controlling the position of the hand member to which the finger member is attached is provided. By controlling the position of the hand member, the object to be grasped by the finger member can be more reliably gripped. . Also, when controlling the finger member and the object to be gripped to have the maximum number of contact points, there are more contact points between them based on the position of the object to be gripped and the relative positional relationship between the hand member. Thus, the robot hand can be controlled. Therefore, the object to be grasped can be grasped more reliably.

  Further, the joint angle control means may be configured to control each joint so that the finger members simultaneously contact at the contact points with respect to the object to be grasped.

  As described above, when the finger members simultaneously contact at the contact points with respect to the object to be grasped, it is possible to prevent a situation in which the object to be grasped is brought down or damaged by the finger member that has arrived first.

  Further, provided with a gripping force detecting means provided on the link member for detecting the gripping force of the link member when gripping the object to be gripped, the joint angle control means has a predetermined gripping force detected by the gripping force detecting means. Alternatively, the control of each joint may be terminated when the threshold value is exceeded.

  In this way, when the gripping force detected by the gripping force detection means exceeds a predetermined threshold, the control of each joint is terminated, so that the gripping target can be gripped with the finger of the robot hand with a certain gripping force. An object can be gripped.

  According to the grip control device for a robot hand according to the present invention, it is possible to reliably grip an object with a low risk of falling or damaging the object by a finger member.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a grip control device for a robot hand according to an embodiment of the present invention, FIG. 2 is a side view of the robot hand, and FIG. 3 is a front view of the robot hand.

  As shown in FIG. 1, a robot hand grip control device (hereinafter referred to as “grip control device”) according to this embodiment includes a robot hand 1, an image recognition device 2, a grip posture calculation device 3, and a control device 4. ing.

  2 and 3, the robot hand 1 includes a first finger 11 corresponding to the thumb, a second finger 12 corresponding to the index finger, a third finger 13 corresponding to the middle finger, and a fourth finger corresponding to the ring finger. 14 is provided. Further, the first finger 11 is provided with a first finger first joint 11A, a first finger second joint 11B, and a first finger third joint 11C. One joint 12A, a second finger second joint 12B, and a second finger third joint 12C are provided. Further, the third finger 13 is provided with a third finger first joint 13A, a third finger second joint 13B, and a third finger third joint 13C, and the fourth finger 14 has a fourth finger first joint. One joint 14A, a fourth finger second joint 14B, and a fourth finger third joint 14C are provided.

  The base part of the first finger 11 is provided with a first finger opposing joint 11G that makes the first finger 11 face the second finger 12 to the fourth finger 14. The opposing joint 11G allows the first finger 11 to oppose the second finger 12 to the fourth finger 14 with a vertical direction parallel to the palm 16 described later.

  A second finger swing joint 12 </ b> G that swings the second finger 12 is provided at the base portion of the second finger 12. The swing joint 12 </ b> G enables the second finger 12 to swing around a horizontal axis orthogonal to the palm portion 16. Further, a third finger rocking joint 13G and a fourth finger rocking joint 14G for rocking the third finger 13 and the fourth finger 14 are provided at base portions of the third finger 13 and the fourth finger 14, respectively. ing. The swing joints 13 </ b> G and 14 </ b> G swing the third finger 13 and the fourth finger 14 around a horizontal axis orthogonal to the palm portion 16. The joints 11A to 11C, 12A to 12B, 13A to 13B, 14A to 14B, the opposing joint 11G, and the swing joints 12G to 14G except for the third joints 12C to 14C of the second finger 12 to the fourth finger 14 Is provided with a motor 8 connected to the motor driver 7 shown in FIG.

  In addition, a first finger first link 11D is provided between the first finger first joint 11A and the first finger second joint 11B of the first finger 11, and the first finger second joint 11B and the first finger A first finger second link 11E is provided between the third joint 11C and a first finger third link 11F is provided at the tip of the first finger third joint 11C. A second finger first link 12D is provided between the second finger first joint 12A and the second finger second joint 12B in the second finger 12, and the second finger second joint 12B and the second finger third A second finger second link 12E is provided between the joints, and a second finger third link 12F is provided at the tip of the second finger third joint 12C.

  Further, a third finger first link 13D is provided between the third finger first joint 13A and the third finger second joint 13B in the third finger 13, and the third finger second joint 13B and the third finger A third finger second link 13E is provided between the third joint 13C and a third finger third link 13F is provided at the tip of the third finger third joint 13C. A fourth finger first link 14D is provided between the fourth finger first joint 14A and the fourth finger second joint 14B of the fourth finger 14, and the fourth finger second joint 14B and the fourth finger third A fourth finger second link 14E is provided between the joint 14C and a fourth finger third link 14F is provided at the tip of the fourth finger third joint 14C. Further, a first finger facing link 11H is provided between the first finger facing joint 11G and the first finger first joint 11A. A second finger swing link 12H is provided between the second finger swing joint 12G and the second finger first joint 12A. Similarly, between the third finger swing joint 13G and the third finger first joint 13A, and between the fourth finger swing joint 14G and the fourth finger first joint 14A, respectively A three-finger swing link and a fourth finger swing link are provided.

  The robot hand 1 also has a thumb ball 15 and a palm portion 16 which are palm members of the present invention. A first finger 11 is attached to the thumb ball 15. The thumb ball 15 is rotatable about the vertical axis, and the first finger 11 is rotatable about the vertical axis together with the thumb ball 15. A second finger 12 to a fourth finger 14 are attached to the palm portion 16. Further, each of the links 11D to 11F, 12D to 12F, 13D to 13F, and 14D to 14F of the first finger 11 to the fourth finger 14, and the thumb ball 15 and the palm portion 16 have buffer pads (flexible meat) 17 respectively. It is attached.

  When gripping an object with the robot hand 1, the first finger 11 turns forward so that the first finger 11 and the third finger 13 face each other. In this way, as schematically shown in FIG. 4, the first finger 11 and the third finger 13 hold an object M to be gripped (hereinafter referred to as “grip target object”) M.

  Further, in the robot hand 1, among the joints of the second finger 12 to the fourth finger 14, the second joint and the third joint are interlocking joints 30. The interlocking joint 30 is provided with a link member 31 between the second joints 12B to 14B and the third joints 12C to 14C.

  The second joints 12B to 14B are provided with motors, but the third joints 12C to 14C are not provided with motors. And when the motor provided in 2nd joint 12B-14B rotationally drives, 2nd joint 12B-14B rotates. Further, when the second joints 12B to 14B rotate, the rotation is transmitted to the third joints 12C to 14C via the link member 31. Thus, the third joints 12C to 14C also rotate together with the second joints 12B to 14B. Here, for convenience of explanation, it is assumed that the joint angles of the second joints 12B to 14B and the joint angles of the third joints 12C to 12D are the same for the second finger 12 to the fourth finger 14 in the robot hand 1. .

  An image recognition apparatus 2 illustrated in FIG. 1 includes a camera serving as an imaging unit and an image processing unit that processes an image captured by the camera. The position, shape, and size of the gripping target object M are recognized by performing image processing on the image captured by the camera with the image processing unit. The image recognition device 2 outputs the recognized position, shape, and size of the gripping target object to the gripping posture calculation device 3 that is a gripping posture calculation means.

  In the present embodiment, the image recognition device 2 functions as an object shape / size recognition device and an object position recognition device. Both of the image recognition apparatuses 2 perform image processing on an image captured by a camera using an image processing unit, and recognize the shape, size, and position of the gripping target object M displayed in the image.

  The gripping posture calculation device 3 selects a gripping calculation method for gripping an object by the robot hand based on the shape of the gripping target object M output from the image recognition device 2, and targets a suitable gripping posture of the robot hand. Calculate as joint angle. The grip posture calculation device 3 stores a grip calculation method corresponding to the model shape of the grip target object M.

  Further, the gripping posture calculation device 3 selects a gripping format for gripping the gripping target object M by the robot hand 1 based on the size of the gripping target object M output from the image recognition device 2, and a suitable robot hand 1. Is calculated as a target joint angle. The gripping posture calculation device 3 stores a gripping format corresponding to the model size of the gripping target object M.

  The gripping posture calculation device 3 has a cylindrical shape, a sphere, and a rectangular parallelepiped shape as the model shape, the contact conditions determined by the constraint conditions of the robot hand, and the shape of the gripping target object M is the model shape. It is stored as a grip calculation method at a certain time. A specific grip calculation method will be described later. The gripping posture calculation device 3 outputs the calculated gripping posture (target joint angle) of the robot hand to the control device 4.

  Connected to the control device 4 are a gripping posture calculation device 3, an encoder / potentiometer 5, a tactile sensor 6, and a motor driver 7. The encoder / potentiometer 5 detects the positions of the first finger 11 to the fourth finger 14 in the robot hand 1 and outputs the detected joint angles of the links of the first finger 11 to the fourth finger 14 to the control device 4. is doing. The tactile sensor 6 is a distributed pressure sensor embedded in the buffer pad 17 shown in FIG. The tactile sensor 6 detects a tactile sensation when the robot hand 1 grips an object with a gripping reaction force, and outputs the detected gripping reaction force to the control device 4.

  The control device 4 performs feedback control based on the joint angles of the links of the first finger 11 to the fourth finger 14 output from the encoder / potentiometer 5 and the target joint angle output from the gripping posture calculation device 3. ing. By this feedback control, an angle command is output to a motor driver 7 that drives a motor provided at each joint of the robot hand 1. Further, the control device 4 outputs an angle command or a speed command to the motor driver 7 so as to correct the gripping posture of the robot hand 1 based on the gripping reaction force output from the touch sensor 6.

  A control procedure in the grip control device for the robot hand according to the present embodiment having the above-described configuration will be described. First, the entire flow in the grip control of the robot hand will be described. FIG. 5 is a flowchart showing a control procedure of the grip control device for the robot hand according to the present embodiment.

  As shown in FIG. 5, when gripping control of the robot hand is performed, the position, shape, and size of the gripping target object M are first recognized (S1). When recognizing the position, shape, and size of the gripping target object M, the image recognition device 2 captures the gripping target object M and performs predetermined image processing to determine the position, shape, and size of the gripping target object M. recognize.

  When the position, shape, and size of the gripping target object M are recognized, the gripping posture calculation device 3 selects a gripping calculation method according to the shape of the gripping target object M (S2). The grip calculation method differs depending on whether the grip target object M is a cylinder, a sphere, or a rectangular parallelepiped, and here, a calculation method corresponding to the grip target object M is selected. Subsequently, a gripping format is selected according to the size of the gripping target object M, and a gripping posture is calculated (S3). The gripping type is selected based on the size of the gripping target object M recognized in step S1, and the gripping posture is calculated according to the selected gripping type. The selection of the gripping type and the calculation of the gripping posture will be further described later.

  After calculating the gripping posture, a time-series target joint angle of each finger that achieves the gripping posture is generated (S4). When the target joint angle is thus generated, a time-series joint angle command is generated according to the target joint angle, the motor 8 is driven and controlled via the motor driver 7, and is gripped by the fingers 11 to 14 and the palm 16. The target object M is gripped (S5).

  At that time, based on the gripping force detected by the tactile sensor 6, the gripping force of each link on each finger by the robot hand 1 is measured (S6), and the gripping force of each link on each measured finger is fed back. Thereafter, it is determined whether or not the measured gripping force is less than an allowable value (S7). As a result, if the measured gripping force is not less than the allowable value, the gripping target object M is gripped by the robot hand 1 and an operation such as transport is performed (S8).

  On the other hand, if the gripping force is less than the allowable value, it is determined whether or not the target joint angle has been reached (S9). As a result, when the target joint angle is not reached, the process returns to step S5 and the motor 8 is continuously driven. Further, when the target joint angle is reached, the position error is compensated so that the target joint angle is further corrected and the finger is continuously operated, and the process returns to step S5.

  Next, a procedure from selection of a gripping format of the gripping target object M to generation of a target joint angle (generation of a gripping posture) will be described. The generation of the target joint angle differs depending on the grasped object to which the model shape is assigned. In the present embodiment, a cylindrical shape, a spherical shape, and a rectangular parallelepiped shape are set as model shapes, and these model shapes are assigned to the gripping target object M. Hereinafter, a procedure from selection of the gripping type of the gripping target object M to generation of the target joint angle when the gripping target object M has a cylindrical shape and a rectangular parallelepiped shape will be mainly described.

[When gripping object M is a cylinder]
Now, a case where the model shape to which the gripping target object M is assigned is a cylindrical shape will be described. When the model shape is a cylindrical shape, first, the gripping format of the gripping target object M is examined based on the allocated cylinder dimensions. As a grip type, in addition to gripping with the first finger 11 to the fourth finger 14, gripping with the palm 16 and the second finger 12 to the fourth finger 14, gripping with only the second finger 12 to the fourth finger 14, In addition, grasping by two robot hands can be considered. Here, a gripping method using the palm 16 and the second finger 12 to the fourth finger 14, a gripping operation using only the second finger 12 to the fourth finger 14, and a gripping method using two robot hands will be described. A method for selecting these gripping formats will be described later.

[Holding with Palm 16 and Second Finger 12 to Fourth Finger 14]
First, a procedure for generating a target joint angle when the object to be grasped M is grasped by the palm 16 and the second finger 12 to the fourth finger 14 will be described. FIG. 6 shows a cross section passing through the center line of the third finger 13 and perpendicular to the palm portion 16. As shown in FIG. 6, an xy coordinate system is set in which a point on a straight line along the palm 16 is a coordinate origin. Coordinates are set on the xy coordinate system, and the object center coordinates (x _c , y _{c) of the} gripping target object M are determined from the geometric relationship between the gripping target object M and the links 13D to 13F of the third finger 13. ) And the equation regarding the joint angle θ _i of the third finger 13 is derived.

Upon obtaining the coordinate x _c in the x direction of the object the center of the gripping target object M, to contact the gripping target object M on the palm portion 16, the following (0) expression holds.

x _c −x ₁₀ = R ₁₀ = r + t ₀ (0)
Here, x ₁₀ : coordinates of the third finger first joint 13A in the X direction
r: radius of the cylindrical body to which the object M to be grasped is assigned
t ₀ : Distance from the coordinate x ₁₀ in the X direction of the third finger first joint 13A to the surface of the palm portion 16 By transforming the above equation (0), the object center of the gripping target object M from the following equation (1) it is possible to obtain the x-coordinate _{x c.}

x _c = r + t ₀ + x ₁₀ (1)
Further, the following equation (2) can be derived for the third finger first link 13D based on the distance relationship between the point and the straight line.

(X _c −x ₁₀ ) cos θ ₁ − (y _c −y ₁₀ ) sin θ ₁ = R ₁₁ (2)
Here, R ₁₁ : distance from the center of the gripping object M to the center of the third finger first link 13D (r + t ₁ )
t ₁ : half of the width of the third finger first link 13D
θ ₁ : Joint angle of the third finger first joint 13A Further, the rotation center axis (x ₁₁ , y ₁₁ ) of the third finger second link 13E is expressed by the following expressions (3A) and (3B).

x ₁₁ = x ₁₀ + L ₁₁ sin θ ₁ (3A)
y ₁₁ = y ₁₀ + L ₁₁ cos θ ₁ (3B)
Here, L ₁₁ : Length of the third finger first link 13D Similarly, the following expression (3) is derived based on the distance relationship between the point and the straight line for the third finger second link 13E. be able to.

_{(X c -x 11) cos (} θ 1 + θ 2) - (y c -y 11) sin (θ 1 + θ 2) = R 12 ··· (3)
Here, R ₁₂ : distance (r + t ₂ ) from the center of the gripping object M to the center of the third finger second link 13E
t ₂ : half the width of the third finger second link 13E
θ ₂ : Joint angle of the third finger second joint 13B Further, the rotation center axis (x ₁₂ , y ₁₂ ) of the third finger third link 13F is expressed by the following expressions (4A) and (4B).

x ₁₂ = x ₁₁ + L ₁₂ sin (θ ₁ + θ ₂ ) (4A)
y ₁₂ = y ₁₁ + L ₁₂ cos (θ ₁ + θ ₂ ) (4B)
Here, L ₁₂ : Length of the third finger second link 13E Similarly, the following expression (3) is derived based on the distance relationship between the point and the straight line for the third finger third link 13F. can do.

(X _c −x ₁₂ ) cos (θ ₁ + 2θ ₂ ) − (y _c −y ₁₂ ) sin (θ ₁ + 2θ ₂ ) = R ₁₃ (4)
Here, R ₁₃ : distance from the center of the gripping object M to the center of the third finger third link 13F (r + t ₃ )
t ₃ : Half of the width of the third finger third link 13F Up to this point, in the above equations (1) to (4), there are four unknown variables θ ₁ , θ ₂ , x _c , and y _c . Since there are four equations, the only solution can be obtained. However, since the expressions (2) to (4) are expressions using trigonometric functions, it is not easy to obtain an analytical solution. Therefore, each variable is determined by the procedure shown in the flowchart of FIG. FIG. 7 is a flowchart showing a procedure for determining the gripping posture of the third finger.

First, based on equation (1), calculates the center coordinates _{x c} in the X-axis direction of the gripping target object M (S11). Then, as the search variables _{y c,} it sets an arbitrary initial value of _{y c} (S12). Next, an arbitrary angle θ ₀₁ is set as the joint angle θ ₁ of the third finger first joint 13A (S13).

Subsequently, the term on the left side in the equation (2) is defined as d1, and d1 is calculated (S14). Then, determine the actual absolute value of the difference from the center of the gripping target object M and the distance R ₁₁ to the center of the third finger first link 13D the calculated value d _1, the allowable error e this absolute value is predetermined It is determined whether or not the following is true (S15). The allowable error e is a positive constant smaller than 1.

As a result, the absolute value of the actual distance R ₁₁ and calculation values d1 is, if it is determined to exceed the allowable error e adds Δθ to the joint angle theta ₁ of the third finger first joint 13A (S16) Return to step S14. Here, Δθ is determined by an equation of α (d ₁ −R ₁₁ ). Α is a preset adjustment gain.

On the other hand, in step S15, the absolute value of the difference between the calculated value d ₁ and distance R ₁₁ is, when it is determined that the allowable is the error e or less, as the joint angle theta ₂ of the third finger second joint 13B, optionally Of the angle θ ₀₂ (S17). Subsequently, the left term in equation (3) and _{d 2,} to calculate a _{d 2} (S18). Then, determine the actual absolute value of the difference from the center of the gripping target object M and the distance R ₁₂ to the center of the third finger second link 13E and calculated value d _2, the allowable error e this absolute value is predetermined It is determined whether or not the following is true (S19). This allowable error e is equivalent to the above-described allowable error. However, different tolerances can be used.

As a result, when it is determined that the absolute value of the calculated value d ₂ and the distance R ₁₂ exceeds the allowable error e, Δθ is added to the joint angle θ ₂ of the third finger second joint 13B (S20), The process returns to step S18. Here, Δθ is determined by the equation of α (d ₂ −R ₁₂ ). Α is a preset adjustment gain as in the above equation.

On the other hand, in step S19, the absolute value of the difference between the calculated value d ₂ and a distance R ₁₂ is, when it is determined that the allowable error e below, the left-hand side terms in equation (4) and d _3, grip Substituting the X coordinate x _c , Y coordinate y _c of the object center coordinate of the target object M, the joint angle θ _{1 of} the third finger first joint 13A, and the joint angle θ ₂ of the third finger second joint 13B, and d ₃ is calculated (S21). Then, determine the actual absolute value of the difference from the center of the gripping target object M and the calculated value d ₃ and distance R ₁₃ to the center of the third finger third link 13F, permissible error e this absolute value is predetermined It is determined whether or not the following is true (S22).

As a result, when it is determined that the absolute value of the calculated value d ₃ and the distance R ₁₃ exceeds the allowable error e, Δy _c is added to the Y coordinate y _c of the center coordinate of the gripping target object M (S23). Then, the Y coordinate y _c of the object center coordinate of the gripping target object M is changed, and the process returns to step S13. Thus, a new calculation is performed. Here, Δyc is a predetermined length. In addition, β is a preset adjustment gain, similar to α described above.

Thus repeated loop in steps S16, S20, S23, when the calculated value _{d 3} was the actual distance _{R 13} or more at the final step S22, it is considered that stable gripping condition is satisfied. In this way, the target joint angle (gripping posture) of the third finger 13 can be obtained.

  When the target joint angle of the third finger 13 is obtained, the gripping postures of the second finger 12 and the fourth finger 14 are subsequently obtained. Since the method of obtaining the holding posture of the second finger 12 and the fourth finger 14 is the same, the method of obtaining the holding posture of the second finger 12 will be described.

  As a method for obtaining the gripping posture of the second finger 12, the relationship between the links 12D to 12F of the second finger 12 and the gripping target object M is as described in (2) above when the gripping posture of the third finger 13 is obtained. ) To (4) can be applied as they are. However, here, after determining the grip shape of the third finger 13, the center of the gripped object has already been determined, the second finger 12 has an interlocking joint, and the parameters are the same as those of the third finger 13. is not. For this reason, it is not possible to apply the method of obtaining the holding posture and the holding posture of the third finger 13.

  Further, the second finger 12 has three links 12D to 12F, but since one joint is an interlocking joint among the three joints, there are only two active joints. Further, since the center position of the gripping target object M cannot be adjusted, two links out of the three links of the second finger 12 can always be brought into contact with the gripping target object M. Furthermore, it is necessary to check the gaps between the links 12D to 12F and the gripping target object M so that the other one link does not bite into the gripping target object M. Here, in order to realize stable gripping, the joint angle is set with priority given to arranging contact points between the links 12D to 12F of the second finger 12 and the gripping target object M on both sides of the center of the gripping target object M. Ask. Furthermore, the joint angle is obtained so that the second finger first link 12D and the second finger third link 12F are brought into contact with the grasped object M as much as possible. When the second finger first link 12D and the second finger third link 12F cannot contact the gripping target object M, the second finger second link 12E and the second finger third link 12F are gripped by the gripping target object M. To make contact. The procedure will be described with reference to FIG. FIG. 8 is a flowchart showing a procedure for determining the gripping posture of the second finger.

As shown in FIG. 8, when determining the holding posture of the second finger 12, first, an arbitrary angle θ ₁₀ is set as the joint angle θ ₁ of the second finger first joint 12A (S31). Next, the (2) by substituting theta ₁₀ in formula, the value of the left side of the terms in equation (2) as _{d 1,} calculates the _{d 1} (S32).

Subsequently, the value of the left side of the terms in equation (2) and d _1, the absolute value of the difference between the distance R ₁₁ from the center of the gripping target object M to the center of the second finger first link 12D sought, this It is determined whether or not the absolute value is within a predetermined allowable error e (S33). As a result, if the absolute value is not within the allowable error e adds the Δθ to θ ₁ (S34), the flow returns to step S32. Here, Δθ is determined by the equation of α (d ₁ -R ₁₁ ). Α is a preset adjustment gain.

On the other hand, the absolute value in the step S33 is if it is determined to be within the scope of the allowable error e as joint angle theta ₂ of the second finger second joint 12B, to set an arbitrary angle θ ₂₀ (S35). Subsequently, the (4) by substituting theta ₂₀ in formula, the left-hand side terms in equation (4) as _{d 3,} to calculate a _{d 3} (S36). Then, the (4) and the left side of the section d ₁ of formula, the absolute value of the difference between the distance R ₁₃ from the center of the actual gripping target object M to the center of the second finger second link 12E, the absolute value Is within a predetermined allowable error e (S37).

As a result, if the absolute value is not within the allowable error e adds the Δθ to θ ₂ (S38), the flow returns to step S36. Here, Δθ is determined by the equation α (d ₃ −R ₁₃ ). Α is a preset adjustment gain. On the other hand, the absolute value in step S37 is if it is judged to be within the scope of permissible error e, the left term of equation (3) and d _2, to calculate a d ₂ (S39).

Then, equation (3) of the left side of the section d ₂ is actually larger it determines whether than gripping target object distance R ₁₂ from the center of M to the center of the second finger second link 12E (S40). As a result, when it is determined that d ₂ is equal to or less than R ₁₂ , a predetermined angle ε is subtracted from θ ₁ (S41), and the process returns to step S35. On the other hand, if it is determined that d ₂ exceeds R ₁₂ , the joint angles θ ₁ and θ ₂ are determined, and the process ends.

  In this way, it is possible to generate a target joint angle when the object to be grasped M is grasped by the palm portion 16 and the second finger 12 to the fourth finger 14.

[Grip only by the second finger 12 to the fourth finger 14]
Next, generation of the target joint angle when the object to be grasped M is grasped only by the second finger 12 to the fourth finger 14 will be described. As shown in FIG. 9, an xy coordinate system is set in which a point on a straight line along the palm 16 is a coordinate origin. Coordinates are set on the xy coordinate system, and the object center coordinates (x _c , y _{c) of the} gripping target object M are determined from the geometric relationship between the gripping target object M and the links 13D to 13F of the third finger 13. ) And the equation regarding the joint angle θ _i of the third finger 13 is derived.

First, the constraint condition of the object center coordinates (x _c , y _c ) of the gripping target object M is examined. When the gripping target object M contacts the third finger first link 13D, the following equation (5) is established in the coordinate system of the third finger first link 13D. Here, (x _c1 , y _c1 ) is the center coordinates of the gripping target object M in the coordinate system of the third finger first link 13D.

x _c1 = R ₁₁ = r + t ₁ (5)
In this gripping type, it is possible to arbitrarily set the joint angle theta ₁ of the finger. In the wrist coordinate system, the object center coordinates (x _c , y _c ) of the gripping target object M can be obtained by the following two expressions.

x _c = x _c1 cos θ ₁ + y _c1 sin θ ₁ + x ₁₀
y _c = −x _c1 sin θ ₁ + y _c1 cos θ ₁ + x ₁₀ (6)
Further, the rotation center coordinates (x ₁₁ , y ₁₁ ) of the third finger second link 13E can be obtained by the following equations (7A) and (7B).

x ₁₁ = x ₁₀ + L ₁₁ sin θ ₁ (7A)
y ₁₁ = y ₁₀ + L ₁₁ cos θ ₁ (7B)
Furthermore, the following equation (7) can be derived for the third finger second link 13E based on the distance relationship between the point and the straight line. Θ ₂ is the joint angle of the third finger second joint 13B.

_{(X c -x 11) cos (} θ 1 + θ 2) - (y c -y 11) sin (θ 1 + θ 2) ··· (7)
Similarly, the rotation coordinate system (x ₁₂ , y ₁₂ ) of the third finger third link 13F can be obtained by the following equations (8A) and (8B).

x ₁₂ = x ₁₁ + L ₁₂ sin (θ ₁ + θ ₂ ) (8A)
y ₁₂ = y ₁₁ + L ₁₂ cos (θ ₁ + θ ₂ ) (8B)
Similarly, the following equation (8) can be derived for the third finger third link 13F based on the distance relationship between the point and the straight line.

_{(X c -x 12) cos (} θ 1 + 2θ 2) - (y c -y 12) sin (θ 1 + 2θ 2) = R 13 ··· (8)
The grip shape of the third finger 13 can be determined using these equations (5) to (8). Hereinafter, the procedure for determining the gripping posture of the third finger will be described with reference to the flowchart shown in FIG.

First, based on the above equation (5), the center x coordinate x _c1 of the gripping target object M in the coordinate system of the third finger first link 13D is calculated (S51). Next, to set the joint angle theta ₁ of the third finger first joint 13A (S52). Here, the joint angle θ ₁ can be set to an arbitrary angle.

Subsequently, an initial value of the center y coordinate y _c1 of the gripping target object M in the coordinate system of the third finger first link 13D is set (S53). The initial value of the center y coordinate y _c1 can be set at an arbitrary position. Then, the object center coordinates (x _c , y _c ) of the gripping target object M in the wrist coordinate system are calculated (S54). The object center coordinates (x _c , y _c ) of the gripping target object M in the wrist coordinate system can be obtained by the above equation (6).

Next, the joint angle theta ₂ of the third finger second joint 13B, to set an arbitrary angle θ ₀₂ (S55). Then, by substituting theta ₀₂ in equation (7), the value of the left side terms in equation (7) as _{d 2,} and calculates the _{d 2} (S56). Subsequently, the value of the left side terms in equation (7) and d _2, the absolute value of the difference between the distance R ₁₂ from the center of the gripping target object M to the center of the third finger second link 13E sought, this It is determined whether or not the absolute value is within a predetermined allowable error e (S57). As a result, if the absolute value is not within the allowable error e adds the Δθ to θ ₂ (S58), the flow returns to step S56.

On the other hand, the absolute value in step S57 is if it is determined to be within a predetermined range of tolerance e is the value of the left side terms in equation (8) as d _3, and calculates a d ₃ (S59). Subsequently, the value of the left side terms in equation (8) and d _3, from the center of the actual gripping target object M absolute value of the difference between the distances R ₁₃ to the center of the third finger second link 13E determined Then, it is determined whether or not the absolute value is within a predetermined allowable error e (S60). As a result, if the absolute value is not within the allowable error e, Δy _c1 is added to y _c1 (S61), and the process returns to step S54. Here, Δy _c1 is determined by the equation of β (d ₃ −R ₁₃ ). Β is a preset adjustment gain.

On the other hand, if it is determined in step S60 that the absolute value is within the range of the predetermined allowable error e, the center y coordinate y _c1 of the object to be grasped M and the joint angle θ _{2 of} the third finger second joint 13B are determined. Determine and end the process.

  Further, the joint angles of the second finger 12 and the fourth finger 14 are a method of generating a target joint angle in the case of gripping the gripping target object M in a gripping manner by the palm portion 16 and the second finger 12 to the fourth finger 14. It can be generated in the same way. In this way, it is possible to generate a target joint angle when the object to be grasped M is grasped only by the second finger 12 to the fourth finger 14.

[Grip by two robot hands]
On the other hand, there are cases where the gripping target object M is large and cannot be gripped by one robot hand 1. In this case, the object M to be grasped can be grasped using two robot hand members. The procedure for determining the gripping posture of one robot hand 1 and the center of the gripping target object M when gripping the gripping target object M using the two robot hands 1 is the palm 16 and the second finger 12 to the fourth finger 14. This is the same as the case of gripping the gripping target object M by using. Further, when calculating the gripping posture of the other robot hand 1, the above formulas (2) to (4) and the flowchart showing the procedure for determining the gripping posture shown in FIG. 8 can be applied as they are.

[Select gripping type]
Next, a procedure for selecting a gripping format and calculating a gripping posture according to the size of the gripping target object M will be described. When the diameter of the cylinder that is the object to be grasped M is within a certain range, it can be grasped by the first finger 11 and the second finger 12 to the fourth finger 14. If it is smaller than this range, the first finger 11 and the second finger 12 to the fourth finger 14 cannot be held, and the palm 16 and the second finger 12 to the fourth finger 14 are used up to a certain range. Grasping is possible. When the range is further smaller, gripping by only the second finger 12 to the fourth finger 14 is possible up to a certain range. When it becomes smaller than that, it is impossible to wrap and hold the robot hand 1. Further, when the diameter of the cylinder is larger than the range in which the object M to be grasped can be grasped by the first finger 11 and the second finger 12 to the fourth finger 14, gripping by using a pair of robot hands 1 is possible. It becomes. Therefore, a gripping format is selected and a gripping shape is calculated according to the procedure shown in FIG. By determining the gripping format according to the following procedure, a suitable gripping format can be automatically selected.

  FIG. 11 is a flowchart illustrating a procedure for selecting a gripping format, calculating a gripping posture, and gripping the gripping target object M. As shown in FIG. 11, first, the wrapping and gripping posture of the gripping target object M by the first finger 11 and the second finger 12 to the fourth finger 14 is calculated (S71). As shown in FIG. 12, the enveloping and gripping shape refers to a shape in which the gripping target object M is gripped by the first finger 11 and the second finger 12 to the fourth finger 14. In determining the enveloping grip shape, the center of the gripping object M and the joint angles of the second finger 12 to the fourth finger 14 can be determined using the above equations (1) to (4). Also, the joint angle of the first finger 11 can be obtained by a similar calculation formula.

  When the joint angles of the respective joints of the first finger 11 to the fourth finger 14 are obtained, it is determined whether or not the portion where the gripping target object M is wrapped in the robot hand 1 is more than half of the gripping target object M (S72). ). Therefore, the validity of this gripping form is examined. Examination of the validity of the gripping format is based on the gripping point positions of the fingertip links (the first finger third link 11F and the third finger third link 13F) of the first finger 11 and the third finger 13 and the gripping object M. This is done by examining the relationship with the center.

The contact point between the first finger third link 11F and the gripping target object M is the gripping point A (x _a , y _a ), and the contact point between the third finger third link 13F and the gripping target object M is the gripping point B (x _b, and _{y b),} these gripping point _{a (x} a, _y a) and the gripping point _{B (x} b, obtaining a _{y b).} First, the position of the gripping point A (x _a , y _a ) of the first finger third link 11F will be described. An equation that is parallel to the center line of the first finger third link 11F and that is a tangent to the object M to be grasped is expressed by the following equation (9).

y = k ₂ (xx ₂₁ ) + y ₂₁ ′ (9)
Here, k ₂ = tan (φ ₁ + φ ₂ )
y ₂₁ ′ = y ₂₁ + t ₂₂ / cos (φ ₁ + φ ₂ )
t ₂₂ : half the thickness of the first finger third link
φ ₁ : joint angle of the first finger second joint 11B
φ ₂ : joint angle of the first finger third joint 11C The equation of the circle indicating the cross section of the object M to be grasped is expressed by the following equation (10).

_{^{(X-x c) 2 +}} (y-y c) 2 = r 2 ··· (10)
The gripping point A (x _a , y _a ) can be calculated by the above equations (9) and (10). These grip points A (x _a , y _a ) can be obtained by two expressions expressed as the following expression (11).

x _a = (k ₂ ² x ₂₁ + x _c −k ₂ y ′ ₂₁ + k ₂ y _c ) / (k ₂ ² +1)
y _a = (y ′ ₂₁ + k ₂ ² y _c −k ₂ x ₂₁ + k ₂ x _c ) / (k ₂ ² +1) (11)
The gripping point A (x _a , y _a ) of the first finger third link 11F can be obtained as described above. Further, the gripping point B (x _b , y _b ) of the third finger third link 13F can be obtained by the following two expressions expressed by the following expression (12) through the same process.

x _b = (k ₁ ² x ₁₂ + x _c −k ₁ y ′ ₁₂ + k ₁ y _c ) / (k ₂ ² +1)
y _b = (y ′ ₁₂ + k ₁ ² y _c −k ₁ x ₁₂ + k ₁ x _c ) / (k ₂ ² +1) (12)
Here, k ₁ = tan (0.5π−θ ₁ −2θ ₂ )
y ₁₂ ′ = y ₁₂ + t ₃ / sin (θ ₁ + 2θ ₂ )
Thus, the gripping point _{A (x} a, _y a) and the gripping point _{B (x b, y} b) After determining the gripping point _{A (x} a, _y a) and the gripping point _{B (x b, y} b) and the holding Based on the positional relationship with the center point of the target object M, it is determined whether or not the following expression (13) is satisfied.

(X _a + x _b ) / 2 ≧ x _c (13)
When the expression (13) is not satisfied, as shown in FIG. 13, the portion where the gripping target object M is gripped by the robot hand 1 is less than half of the entire gripping target object M. In this case, the gripping state becomes unstable. Therefore, when the above equation (13) is not satisfied, the grip shape by the two robot hands 1 (with both hands) is calculated (S73). Thereafter, the object M to be grasped is wrapped and grasped by the two robot hands 1 (S74), and the process is terminated.

On the other hand, if it is determined in step S72 that the expression (13) is satisfied, it is determined whether or not the fingertips of the first finger 11 and the third finger 13 are in contact with each other (S75). The determination as to whether or not the fingertips touch each other is made as follows. The fingertip point D (x _d , y _d ) of the first finger 11 and the fingertip point (inner tip point) of the third finger 13 shown in FIG. ) E (x _e , y _e ) can be obtained by two expressions represented as the following expressions (14) and (15), respectively.

x _d = x ₂₁ + L ₂₂ cos (φ ₁ + φ ₂ ) + t ₂₂ sin (φ ₁ + φ ₂ )
y _d = y ₂₁ + L ₂₂ sin (φ ₁ + φ ₂ ) + t ₂₂ cos (φ ₁ + φ ₂ ) (14)
x _e = x ₁₂ + L ₁₃ sin (θ ₁ + 2θ ₂ ) + t ₃ cos (θ ₁ + 2θ ₂ )
y _e = y ₁₂ + L ₁₃ cos (θ ₁ + 2θ ₂ ) −t ₃ sin (θ ₁ + 2θ ₂ ) (15)
If y _e > y _d as a result of the above equations (14) and (15), it can be determined that the fingertips do not touch each other. In this case, the gripping target object M can be gripped by all of the first finger 11 to the fourth finger 14. Therefore, the object M to be grasped is grasped with the first finger 11 to the fourth finger 14 (S76), and the process is terminated.

On the other hand, when y _e > y _d is not satisfied, it can be determined that the fingertips are in contact with each other. In this case, the wrapping and gripping posture by the second finger 12 to the fourth finger 14, which are fingers other than the palm portion 16 and the first finger 11, is calculated (S77). The calculation of the enveloping grip shape by the second finger 12 to the fourth finger 14, which is a finger other than the palm 16 and the first finger 11, is performed using the above equations (1) to (4), for example, FIG. 7 and FIG. It is performed according to the procedure shown in.

  As a result of the calculation of the wrapped gripping posture, it is determined whether or not the palm 16 and the fingertip of the third finger 13 are in contact with each other in the determined gripping posture (S78). Whether or not the palm 16 and the fingertip of the third finger 13 are in contact can be determined as follows.

As shown in FIG. 14, the fingertip of the third finger 13 has an inner tip point E (x _e , y _e ) and an outer tip point F (x _f , y _f ) as tip points. Among these inner tip point E (x _e , y _e ) and outer tip point F (x _f , y _f ), the inner tip point E (x _e , y _e ) can be obtained by the above equation (15). The outer tip point F (x _f , y _f ) can be calculated by the following equation (16).

x _f = x ₁₂ + L ₁₃ sin (θ ₁ + 2θ ₂ ) −t ₃ cos (θ ₁ + 2θ ₂ )
y _f = y ₁₂ + L ₁₃ cos (θ ₁ + 2θ ₂ ) + t ₃ sin (θ ₁ + 2θ ₂ ) (16)
Now, in the X direction, when x _e ≧ x ₁₀ + t ₀ and x _f ≧ x ₁₀ + t ₀ are established, the palm 16 and the third finger 13 are not in contact with each other. In this case, the object to be grasped M is wrapped and grasped by the palm portion 16 and the second finger 12 to the fourth finger 14 (S79).

On the other hand, if at least one of x _e ≧ x ₁₀ + t ₀ and x _f ≧ x ₁₀ + t ₀ does not hold, the palm portion 16 and the third finger 13 will come into contact with each other. The object M to be grasped cannot be grasped by the second finger 12 to the fourth finger 14. In this case, the wrapping and gripping posture with only the second finger 12 to the fourth finger 14 is calculated (S80). The calculation of the wrapping and gripping posture by the second finger 12 to the fourth finger 14 is performed, for example, according to the procedure shown in FIG. 10 using the above equations (5) to (8).

  Then, it is determined whether or not there is a solution as a result of calculating the wrapping and gripping posture with the second finger 12 to the fourth finger 14 (S81). As a result, if there is a solution, the object M to be grasped is grasped in the form of wrapping grasping by the second finger 12 to the fourth finger 14 (S82). On the other hand, if there is no solution, it is determined that gripping is impossible (S83). Thus, the process ends.

[When gripping object M is a rectangular parallelepiped]
Next, the case where the model shape to which the gripping target object M is assigned is a rectangular parallelepiped shape. When the model shape is a rectangular parallelepiped shape, first, a grasping format of the grasping target object M is examined based on the dimension of the assigned rectangular parallelepiped shape. As a grip type, in addition to gripping with the first finger 11 to the fourth finger 14, gripping with the palm 16 and the second finger 12 to the fourth finger 14, gripping with only the second finger 12 to the fourth finger 14, In addition, grasping by two robot hands can be considered. Here, a gripping method using the palm 16 and the second finger 12 to the fourth finger 14, a gripping operation using only the second finger 12 to the fourth finger 14, and a gripping method using two robot hands will be described. A method for selecting these gripping formats will be described later.

[Holding with Palm 16 and Second Finger 12 to Fourth Finger 14]
Here, as shown in FIG. 15A, the length of the gripping target object M in the X direction (hereinafter referred to as “the width of the gripping target object”) L, the length in the Y direction (height, hereinafter referred to as “the gripping target object”). Think of it as H). Further, the width L of the gripping target object M is considered to be greater than or equal to the height H of the gripping target object M. As shown in FIG. 15B, when the width L of the gripping target object M satisfies the formula shown as the following formula (17), it is applied to a gripping mode using the palm portion 16 and the second finger 12 to the fourth finger 14. can do.

L ₁₁ −t ₀ −L _a <L <L ₁₁ −t ₀ −t ₂ (17)
Here, L _a : From the tip of the second finger third link 12F when the tip of the second finger third link 12F contacts the second finger first link 12D to the rotation center of the second finger second joint 12B Distance Grasping by the palm 16 and the second finger 12 to the fourth finger 14 has two gripping methods depending on the height H of the gripping target object M. The two methods will be described below.

[First grasping method using palm 16 and second finger 12 to fourth finger 14]
In the first gripping method using the palm part 16 and the second finger 12 to the fourth finger 14, as shown in FIG. 16, the gripping target object M is arranged along the palm part 16 and the second finger first The side surface of the link 12D and the side surface of the second finger third link 12F are brought into contact with the gripping target object M, and the gripping target object M is gripped. In the first method, the gripping target object M can be gripped when the following expression (18) holds.

H> L ₁₂ −t ₁ −t ₃ (18)
Next, a procedure for determining the center coordinates (x _c , y _c ) of the gripping target object M and the joint angle θ _i of the second finger 12 based on the geometric relationship between the gripping target object M and each link of the second finger 12 will be described. To do. The gripping target object M Upon contacting the palm portion 16, the center coordinates x _c of the gripping target object M in the X direction can be expressed by the following equation (19).

x _c = x ₁₀ + L / 2 + t ₀ (19)
On the other hand, the center coordinate y _c of the gripping target object M in the Y direction is within the range represented by the following equation (19S).

y _c ≦ y ₁₀ −H / 2−t ₁ (19S)
Next, the joint angle θ ₁ of the second finger first joint 12A is determined. The distance from the contact point B (x _b , y _b ) between the gripping object M and the second finger first link 12D to the center line of the second finger first link 12D can be expressed by the following equation (2). .

(X _b −x ₁₀ ) cos θ ₁ − (y _b −y ₁₀ ) sin θ ₁ = t ₁ (20)
Further, the joint angle θ ₂ of the second finger second joint 12B is determined. The rotation center coordinates (x ₁₁ , y ₁₁ ) of the second finger second joint 12B can be expressed by the following equations (21A) and (21B).

x ₁₁ = x ₁₀ + L ₁₁ sin θ ₁ (21A)
y ₁₁ = y ₁₀ + L ₁₁ cos θ ₁ (21B)
Similarly, the rotation center coordinates (x ₁₂ , y ₁₂ ) of the second finger third joint 12C can be expressed by the following equations (21C) and (21D).

x ₁₂ = x ₁₁ + L ₁₂ sin (θ ₁ + θ ₂ ) (21C)
y ₁₂ = y ₁₁ + L ₁₂ cos (θ ₁ + θ ₂ ) (21D)
With respect to the second finger third link 12F, the second point from the corner point A (x _a , y _a ) of the gripping target object M located immediately below the contact point B between the gripping target object M and the second finger first link 12D. The distance to the second finger third link 12F can be expressed by the following equation (21).

(X _a −x ₁₂ ) cos (θ ₁ + 2θ ₂ ) − (y _a −y ₁₂ ) sin (θ ₁ + 2θ ₂ ) = t ₃ (21)
Using the above equation (21) obtains the joint angle theta ₂ of the second finger second joint 12B. Further, the joint angles of the third finger 13 and the fourth finger 14 can be obtained in the same manner as the joint angle of the second finger 12 is obtained. In this way, the holding posture of the second finger 12 to the fourth finger 14 can be obtained.

[Second Gripping Method Using Palm 16 and Second Finger 12 to Fourth Finger 14]
In the second gripping method using the palm part 16 and the second finger 12 to the fourth finger 14, as shown in FIG. 17, the gripping target object M is arranged along the palm part 16 and the second finger first The side surface of the link 12D and the tip of the second finger third link 12F are brought into contact with the gripping target object M to grip the gripping target object M. In the second method, the gripping target object M can be gripped when the following formula (22) is satisfied.

H ≦ L ₁₂ −t ₁ −t ₃ (22)
The procedure for determining the center coordinates (x _c , y _c ) of the gripping target object M and the joint angle θ ₁ of the second finger first joint 12A is the same as the first method. Further, describing the procedure for determining the joint angle theta ₂ of the second finger second joint 12B below.

The position of the inner front end point E (x _e , y _e ) of the second finger third link 12F can be expressed by two expressions shown as the following expression (23).

x _e = x ₁₂ + L ₁₃ sin (θ ₁ + 2θ ₂ )
y _e = y ₁₂ + L ₁₃ cos (θ ₁ + 2θ ₂ ) (23)
When y _e in the above equation (23) is satisfied, it is considered that the inner front end point E (x _e , y _e ) of the second finger third link 12F comes into contact with the grasped object M. Therefore, the joint angle θ ₂ of the second finger second joint 12B can be obtained by the following equation (24).

y _e = y ₁₂ + L ₁₃ cos (θ ₁ + 2θ ₂ ) = y _c −H / 2 + t ₃ / sin (θ ₁ + 2θ ₂ ) (24)
Subsequently, it is examined whether or not the second finger second link 12E is in contact with the gripping target object M. As shown in FIG. 17, the corner point A (x _a , y _a ) in the gripping target object M is _a part that is most likely to come into contact with the second finger second link 12E. A distance d from the corner point A (x _a , y _a ) to the center of the second finger second link 12E can be expressed by the following equation (25).

d = (x _a −x ₁₁ ) cos (θ ₁ + θ ₂ ) − (y _a −y ₁₁ ) sin (θ ₁ + θ ₂ ) (25)
The distance d calculated in the above (25) equation is greater than half t ₂ of the width of the second finger second link 12E is never second finger second link 12E in contact with the gripping target object M. Conversely, when the distance d calculated in the above (25) is half t ₂ following the width of the second finger second link 12E, it is the second finger second link 12E in contact with the gripping target object M become. At this time, the second finger first link 12 </ b> D and the second finger second link 12 </ b> E are brought into contact with the object to be grasped M and wrapped and grasped. Then, the joint angle θ2 of the second finger second joint 12B can be obtained by the following equation (26), and the gripping posture of the second finger 12 can be calculated.

(X _a −x ₁₁ ) cos (θ ₁ + θ ₂ ) − (y _a −y ₁₁ ) sin (θ ₁ + θ ₂ ) = t ₂ (26)
Further, the joint angles of the third finger 13 and the fourth finger 14 can be obtained in the same manner as the joint angle of the second finger 12 is obtained. In this way, the holding posture of the second finger 12 to the fourth finger 14 can be obtained.

[Grip only by the second finger 12 to the fourth finger 14]
In gripping with only the second finger 12 to the fourth finger 14, as shown in FIG. 18, the gripping object M is arranged along the side surface of the second finger first link 12D, and the second finger second link 12E. And the side surface of the second finger third link 12F are brought into contact with the gripping target object M to grip the gripping target object M. When the width L of the gripping target object M satisfies the condition shown in the following formula (27), gripping with only the second finger 12 to the fourth finger 14 can be performed.

L ≦ L ₁₁ −t ₀ −L _a (27)
Here, the constraint condition of the center coordinates (x _c , y _c ) of the gripping target object M is first examined. In order to bring the gripping target object M into contact with the second finger first link 12D, the following equation (28) is established in the coordinate system of the second finger first link 12D. The center coordinates of the object in the coordinate system of the second finger first link 12D are (x _c1 , y _c1 ).

x _c1 = H / 2 + t ₁ (28)
The gripping by only the second finger 12 to the fourth finger 14, the joint angle theta ₁ of the second finger first joint 12A can be set to any angle. In the wrist coordinate system, the center coordinates (x _c , y _c ) of the gripping target object M are expressed by the following two expressions.

x _c = x _c1 cos θ ₁ + y _c1 sin θ ₁ + x ₁₀
y _c = −x _c1 sin θ ₁ + y _c1 cos θ ₁ + y ₁₀ (29)
The rotation center coordinates of the second finger second link 12E _{(x 11, y} 11) can be obtained by the following (30A) formula and (30B) expression.

x ₁₁ = x ₁₀ + L ₁₁ sin θ ₁ (30A)
y ₁₁ = y ₁₀ + L ₁₁ cos θ ₁ (30B)
Furthermore, the relationship between the half t ₂ of the distance from the corner point B in gripping target object M to the center of the second finger second link 12E and the width of the second finger second link 12E, the following equation (30) holds.

_{(X b -x 11) cos (} θ 1 + θ 2) - (y b -y 11) sin (θ 1 + θ 2) = t 2 ··· (30)
Further, the rotation center coordinates (x ₁₂ , y ₁₂ ) of the second finger third link 12F can be obtained by the following equations (31A) and (31B).

x ₁₂ = x ₁₁ + L ₁₂ sin (θ ₁ + θ ₂ ) (31A)
y ₁₂ = y ₁₁ + L ₁₂ cos (θ ₁ + θ ₂ ) (31B)
Furthermore, the relationship between the corner point A in gripping target object M and half t ₃ of the distance to the center of the third link 12F width of the second finger third link 12F, the following equation (31) holds.

(X _a −x ₁₂ ) cos (θ ₁ + 2θ ₂ ) − (y _a −y ₁₂ ) sin (θ ₁ + 2θ ₂ ) = t ₃ (31)
The holding posture of the second finger 12 can be determined using the equations (28) to (31). First, the center x coordinate x _c1 of the gripping target object M in the coordinate system of the second finger first link 12D is obtained from the above equation (28). Next, to set the joint angle theta ₁ of the second finger first joint 12A at an arbitrary angle. Then, using the center y coordinate y _c1 of the gripping target object M in the coordinate system of the second finger first link 12D as a search variable, starting from an arbitrary initial value, and using the equations (29) to (31), The joint angle θ ₂ of the second finger second joint 12B and the center coordinates (x _c , y _c ) of the object to be grasped M in the wrist coordinate system can be obtained.

  For the third finger 13 and the fourth finger 14, the gripping posture can be obtained by the same procedure as that for the second finger 12. In this way, it is possible to obtain the gripping posture when gripping the gripping target object M with only the second finger 12 to the fourth finger 14.

[Grip by two robot hands]
When the width L and the height H of the gripping target object M satisfy the conditions of the two formulas shown as the following formula (32), gripping is performed by two robot hands.

L ≧ L ₁₁ −t ₀ −t ₂
H ≧ H ₀ + L ₁₁ −t ₀₁ −t ₂ (32)
Here, H ₀ : distance from the root of the first finger 11 to the root of the second finger 12 in the Y direction t ₀₁ : the width of the first finger second link 11E (= the width of the first finger third link 11F) Half When gripping target object M is gripped by two robot hands, the position and orientation of the wrist in the two robot hands can be determined according to the position and orientation of gripping target object M. Further, the gripping shape of the robot hand 1 is its initial shape. In this way, the object M to be grasped can be grasped by the two robot hands.

[Select gripping type]
Next, a procedure for selecting a gripping format and calculating a gripping shape according to the size of the gripping target object M will be described. As in the case where the gripping target object M is a cylinder, the gripping format can be selected based on the dimensions of the width L and the height H of the gripping target object M. Hereinafter, the procedure for selecting the gripping format will be described with reference to FIG. By determining the gripping format according to the following procedure, a suitable gripping format can be automatically selected.

FIG. 19 is a flowchart showing a procedure for selecting a gripping format, calculating a gripping posture, and gripping the gripping target object M. As shown in FIG. 19, when selecting the gripping format, first, the dimensions of the gripping target object M by image recognition are recognized by the image recognition device 2 shown in FIG. 1 (S91). Next, it is determined whether or not the recognized size of the gripping target object M satisfies L ≧ L ₁₁ −t ₀ −t ₂ , which is one of the two formulas represented by the above formula (32) (S 92). .

As a result, when it is determined that L ≧ L ₁₁ −t ₀ −t ₂ is satisfied, it is determined whether or not the following expression (33) is satisfied (S 93).

H ₀ −t ₁₀ −t ₂ <H <H ₀ + L ₁₁ −t ₁₀ −t ₂ (33)
As a result, when it is determined that the expression (S33) is satisfied, enveloping and gripping using the first finger 11 to the fourth finger 14 is possible without using two robot hands. Therefore, wrapping and gripping is performed using the first finger 11 to the fourth finger 14 (S94). On the other hand, when it is determined that the above expression (33) is not satisfied, the single robot hand cannot be wrapped and held. For this reason, when it is determined that the above equation (33) is not satisfied, the wrapping and gripping using two robot hands is performed (S95).

If it is determined in step S92 that L ≧ L ₁₁ −t ₀ −t ₂ is not satisfied, it is determined whether or not the above equation (27) is satisfied (S96). As a result, when it is determined that the expression (27) is not satisfied, it is determined whether or not the expression (18) is satisfied (S97). As a result, when it is determined that the expression (18) is satisfied, wrapping and holding is performed by the first holding method using the palm portion 16 and the second finger 12 to the fourth finger 14 (S98), and it is determined that the expression is not satisfied. In such a case, wrapping and gripping are performed by the second gripping method using the palm portion 16 and the second finger 12 to the fourth finger 14 (S99).

  Further, when it is determined in step S96 that the above expression (27) is satisfied, the grip shape (grip posture) is calculated according to the grip form by gripping with only the second finger 12 to the fourth finger 14 (S100), and the solution is It is determined whether or not there is (S101). As a result, when it is determined that there is a solution, gripping with only the second finger 12 to the fourth finger 14 is performed based on the obtained solution. On the other hand, if it is determined that there is no solution, it is determined that gripping is impossible (S102). In this way, the process ends.

  As described above, in the grip control device for the robot hand according to the present embodiment, the target joint angle is set according to the shape of the gripping target object M regardless of whether the finger has an interlocked joint or not. By setting, the gripping posture of the finger is calculated and the gripping target object M is gripped.

  In the robot hand disclosed in Patent Document 2, an appropriate gripping position is calculated in order to grip the gripping target object M with the robot hand. However, even if the hand reaches an accurate gripping position, stable wrapping and gripping is not always possible unless the active joints of the fingers are operated cooperatively.

  In contrast, the robot hand gripping control device according to the present embodiment calculates the target position of each joint of each finger in advance after deriving the enveloping gripping condition having the most gripping contact points. Yes. For this reason, the object M to be grasped can be reliably grasped by the robot hand.

  In the robot hand gripping control apparatus according to the embodiment, a plurality of predefined model shapes and contact conditions determined from the constraint conditions of the robot hand with respect to the model shapes are stored. Then, any model shape is assigned to the recognized shape of the gripping target object M, and a gripping posture that satisfies the contact condition between the allocated model shape and the palm portion 16 and the second finger 11 to the fourth finger 14 is calculated. is doing. For this reason, there is a low risk of falling or damaging the object with the second finger 11 to the fourth finger 14, and the gripping target object M can be reliably gripped.

  Furthermore, in the robot hand gripping control method according to the present embodiment, any size can be handled as long as the size of the object is within a grippable range. In addition, in the present embodiment, the target shape of each enveloping and gripping is calculated by dividing the object shape into three types: a cylinder, a sphere, and a rectangular parallelepiped. For this reason, it is possible to reliably wrap and hold the three-dimensional object.

  Moreover, in the robot hand gripping control method according to the present embodiment, each finger arrives at the surface of the gripping target object M at the same time. For this reason, it is possible to prevent a situation in which the finger that has reached the gripping target object M first reaches the gripping target object M to move, defeat, or damage the gripping target object M.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. For example, in the above embodiment, a rectangular parallelepiped, a cylinder, or a sphere is set as the model shape, but in addition, those that are relatively likely to be gripped by the robot, such as a ring that is a handle of a cup, are roughly classified. Can be set.

  In the above embodiment, a finger having an interlocking joint and a finger not having an interlocking joint are described as examples. However, when a finger having an interlocking joint is used, a finger having no interlocking joint is used. Compared to the case, there is an advantage that the number of actuators can be reduced by interlocking. Further, as the number of actuators is reduced, the overall control can be simplified and the size of the interlocking joint can be reduced.

  Furthermore, in the above-described embodiment, an image processing device is used as the object shape recognition device and the object position recognition device. However, the present invention is not limited to this, and various devices can be used. For example, as the object shape recognition device, a device that projects light onto an object and estimates the shape from the reflected light can be used. Further, as the object position recognition device, for example, a device that recognizes the shape of an object from an image and detects the position of the object with an ultrasonic wave or the like can be used.

It is a block block diagram of the holding | grip control apparatus of a robot hand. It is a side view of a robot hand. It is a front view of a robot hand. It is a top view which shows the state which hold | grips a cylinder. It is a flowchart which shows the control procedure of the holding | grip control apparatus of a robot hand. It is a figure which shows roughly the side cross section of the state which hold | grips a cylinder with a palm member and a 2nd finger-a 4th finger. It is a flowchart which shows the procedure which determines the holding posture of the 3rd finger at the time of holding | grip a cylinder with a palm member and a 2nd finger-a 4th finger. It is a flowchart which shows the procedure which determines the holding posture of the 2nd finger at the time of holding | grip a cylinder with a palm member and a 2nd finger-a 4th finger. It is a figure which shows schematically the side cross section of the state which hold | grips a cylinder only with a 2nd finger-a 4th finger. It is a flowchart which shows the procedure which determines the holding | grip attitude | position of the 3rd finger at the time of hold | gripping a cylinder only with a 2nd finger-a 4th finger. It is a flowchart which shows the procedure which selects the holding | grip form at the time of holding | grip a cylindrical-shaped holding object object, calculates a holding shape, and holds a holding object object. It is a figure which shows schematically the side cross section of the state which hold | grips a cylinder with a 1st finger-a 4th finger. It is a figure which shows schematically the side cross section of the robot hand for demonstrating the range which can hold | grip a cylinder with a 1st finger-a 4th finger. It is a figure which shows roughly the side cross section of the robot hand for demonstrating the front-end | tip part of the 2nd finger at the time of holding | gripping a cylinder with a palm member and a 2nd finger-a 4th finger. (A) is a side view of the object to be grasped which is a rectangular parallelepiped, and (b) is a side view for explaining each dimension of the second finger. It is a figure which shows schematically the side cross section of the state which hold | grips a cylinder only with a 2nd finger-a 4th finger. It is a figure which shows roughly the side cross section of the 1st state which hold | grips a rectangular parallelepiped with a palm part and a 2nd finger-a 4th finger. It is a figure which shows schematically the side cross section of the 2nd state which hold | grips a rectangular parallelepiped with a palm part and a 2nd finger-a 4th finger. It is a figure which shows schematically the side cross section of the state which hold | grips a rectangular parallelepiped only with a 2nd finger-a 4th finger. It is a flowchart which shows the procedure which selects the holding | grip form at the time of hold | gripping the holding object of a rectangular parallelepiped shape, calculates a holding shape, and holds a holding object.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Robot hand, 2 ... Image recognition apparatus, 3 ... Gripping attitude | position calculation apparatus, 4 ... Control apparatus, 5 ... Encoder / potentiometer, 6 ... Tactile sensor, 7 ... Motor driver, 11 ... First finger, 12 ... Second finger , 13 ... third finger, 14 ... fourth finger, 15 ... thumb ball, 16 ... palm, 17 ... buffer pad, M ... object to be grasped.

Claims (8)

An object to be grasped is controlled by controlling an angle of each joint of the finger member in a hand member having a finger member including a plurality of link members connected via a joint and a palm member to which the finger member is attached. In the grip control device of the robot hand to grip,
A thumb member is disposed at a position facing the finger member across the palm member on one side of the palm member;
As the hand member, a pair of hand members are disposed,
Object shape recognition means for recognizing the shape of the object to be grasped;
Object size recognition means for recognizing the size of the object to be grasped;
Based on the recognized shape of the gripping target object, joint angles when the plurality of link members included in the finger member are in contact with the gripping target object are respectively determined, and the finger member is gripped according to the determined joint angles. A gripping posture calculating means for calculating the posture;
Joint angle control means for controlling the joints so that the finger member is in a posture determined by the gripping posture calculation means;
With
The gripping posture calculation means includes a plurality of predefined model shapes, a gripping calculation method corresponding to the model shape, a gripping format corresponding to the model size of the gripping target object, and a constraint of the robot hand on the model shape Storing the model shape determined from the condition and the contact condition between the palm member and the finger member;
Assign one of the plurality of model shapes to the recognized shape of the gripping object,
From the stored grip calculation methods, select a grip calculation method for gripping an object by the robot hand based on the model shape assigned to the grip target member,
From the stored gripping formats, select a gripping format according to the size of the recognized gripping target object,
Among the stored contact conditions, when gripping the grip target object in the selected grip type, the contact condition between the model shape assigned to the grip target object and the palm member and the finger member When calculating a gripping posture that satisfies the selected gripping calculation method ,
Calculating a gripping posture that satisfies a contact condition between the gripping object and the thumb member and the finger member;
When it is determined that there is no gripping posture that satisfies the contact condition between the model shape and the finger member and the thumb member, a gripping posture that satisfies the contact condition between the model shape and the palm member and the finger member To calculate
When a range covering the model shape assigned to the grip target member by the finger member and the thumb member is smaller than a predetermined range, a grip posture satisfying a contact condition between the pair of hand members and the model shape is calculated. A gripping control device for a robot hand.   The gripping posture that satisfies the contact condition between the model shape and the finger member is calculated when it is determined that there is no gripping posture that satisfies the contact condition between the model shape and the palm member and the finger member. The robot hand grip control device described. At least a part of the joint is an interlocking joint that interlocks a link member to be connected,
The gripping posture calculation means changes the position of the hand member relative to the gripping target object when performing the gripping posture calculation when it is determined that there is no gripping posture that satisfies the contact condition with the palm member and the finger member. The grip control device for a robot hand according to claim 1 or 2 . The contact condition is determined when the model shape assigned to the gripping target object and the finger member have a predetermined number of contact points or more based on the model shape and the constraint condition of the robot hand. The grip control device for a robot hand according to any one of claims 1 to 3 , wherein the position of the finger member with respect to is geometrically determined. Object position recognition means for recognizing the position of the gripping object;
Hand member position control means for controlling the position of the hand member;
With
The robot hand according to any one of claims 1 to 4 , wherein the position of the hand member is controlled based on a relative positional relationship between the position of the recognized object to be grasped and the position of the hand member. Gripping control device. An object to be grasped is controlled by controlling an angle of each joint of the finger member in a hand member having a finger member including a plurality of link members connected via a joint and a palm member to which the finger member is attached. In the grip control device of the robot hand to grip,
Object shape recognition means for recognizing the shape of the object to be grasped;
Object size recognition means for recognizing the size of the object to be grasped;
Based on the recognized shape of the gripping target object, joint angles when the plurality of link members included in the finger member are in contact with the gripping target object are respectively determined, and the finger member is gripped according to the determined joint angles. A gripping posture calculating means for calculating the posture;
Joint angle control means for controlling the joints so that the finger member is in a posture determined by the gripping posture calculation means;
With
The gripping posture calculation means includes a plurality of predefined model shapes, a gripping calculation method corresponding to the model shape, a gripping format corresponding to the model size of the gripping target object, and a constraint of the robot hand on the model shape Storing the model shape determined from the condition and the contact condition between the palm member and the finger member;
Assign one of the plurality of model shapes to the recognized shape of the gripping object,
From the stored grip calculation methods, select a grip calculation method for gripping an object by the robot hand based on the model shape assigned to the grip target member,
From the stored gripping formats, select a gripping format according to the size of the recognized gripping target object,
Among the stored contact conditions, when gripping the grip target object in the selected grip type, the contact condition between the model shape assigned to the grip target object and the palm member and the finger member A gripping posture satisfying is calculated by the selected gripping calculation method,
The joint angle control means generates target joint angles of the joints so that the finger members simultaneously contact at the contact points with respect to the model shape assigned to the object to be grasped, and each joint is set to the target joint. Control to the corner,
When controlling each of the joints to the target joint angle, when the gripping force of the finger member on the gripping target object is equal to or greater than a predetermined allowable value before the joints reach the target joint angle, Grasping the object to be gripped,
When each of the joints reaches the target joint angle before the gripping force of the finger member with respect to the gripping target object exceeds a predetermined allowable value, position error compensation of the target joint angle is performed. Robot hand gripping control device. A gripping force detecting means provided on the link member for detecting the gripping force of the link member when gripping the gripping target object;
The joint angle control means terminates the control of each joint when the gripping force detected by the gripping force detection means exceeds a predetermined threshold value. The grip control device for a robot hand according to claim 1. An object to be grasped is controlled by controlling an angle of each joint of the finger member in a hand member having a finger member including a plurality of link members connected via a joint and a palm member to which the finger member is attached. In the grip control device of the robot hand to grip,
A thumb member is disposed at a position facing the finger member across the palm member on one side of the palm member;
As the hand member, a pair of hand members are disposed,
Object shape recognition means for recognizing the shape of the object to be grasped;
Based on the recognized shape of the gripping target object, joint angles when the plurality of link members included in the finger member are in contact with the gripping target object are respectively determined, and the finger member is gripped according to the determined joint angles. A gripping posture calculating means for calculating the posture;
Joint angle control means for controlling the joints so that the finger member is in a posture determined by the gripping posture calculation means;
With
The gripping posture calculation means stores a plurality of pre-defined model shapes and contact conditions between the robot hand and the model shape determined from the constraint conditions of the robot hand with respect to the model shape,
One of the plurality of model shapes is assigned to the recognized shape of the object to be grasped, and among the stored contact conditions, the assigned model shape, the palm member, the finger member, and the thumb member, Calculate the gripping posture that satisfies the contact condition of
When a range covering the model shape assigned to the grip target member by the finger member and the thumb member is smaller than a predetermined range, a grip posture satisfying a contact condition between the pair of hand members and the model shape is calculated. A gripping control device for a robot hand.

Images